*New low flow toilets – How much money will I save?

The new, low-flow and high-efficiency toilets may be good for the environment, but are they good for my wallet? Many Californians are wondering whether the money saved will be worth the upfront costs. Sure, people know it's good for the environment, but is it good for them? In the following, old toilets are compared to the new, 1.28-gallon per flush (gpf) high-efficiency toilets to make heads/tails of the issue.
Performance: Do High-Efficiency Toilets Stack Up?
People still worry about the performance of high-efficiency and low-flow toilets, and it makes sense that with restrictions on water usage, toilets would necessarily sacrifice power. This was true to some extent before 2003, but innovations in flushing technology are now making high-power, water-efficient toilets the norm. If performance is important to you, look for toilets with MaP test ratings of 1000 g and higher. For more explanation, read my blog: What is the MaP test for toilets, and Why Is It Important?
Water and Money Saved By High-Efficiency Toilets
So far, convenience and luxury are the same for conventional and low-flow toilets, but still, why would anyone willingly shell out the money for new toilets?
Normal toilets use 3.5-7 gallons
New toilets use 1.28 gallons per flush, or less
on average, 4 gallons saved per flush
According to the San Francisco Examiner, by upgrading to high-efficiency toilets, the average American family will save:
87.5 gallons of water each day
$12 in water utilities each month ($360 in 3 years)
Calculating Payback Period
Eventually, the savings gained by upgrading household toilets will outstrip the upfront costs. The only question is: will that happen before the mortgage is paid off. I estimate that upgrading a household in the Bay Area with 2 toilets will pay for itself within 6 years. That is not taking into account government rebates offered through the EPA's WaterSense program, installation costs, or more expensive models.